AngstromCTF_2018: Personal Letter

Have you ever gotten tired of writing your name in the header of a letter? Well now there's a program to do it for you! Navigate to /problems/letter/ on the shell server to try your exploit out!

Write-up

This challenge was slightly tricky in that it was a ROP challenge that had to done with format strings. There will be many solutions to this challenge but essentially I chose to target the Global Offset Table (GOT). Before we can start crafting our exploit, we need to know the addresses of what we are targetting.

printFlag: 0x804872b
exit@GOT: 0x804a030

Knowing that, let's target the last two bytes of our exit GOT table. Next, we craft our exploit and try to execute it.